Mechanism for varying the pitch of screw propellers



r Aug. 12 1924. 1,504,159 H. LEITNER MECHANISM FOR VARYING 'I HE PITCH0F SCREW PROPELLERS Filed April 21 1924 fm/entgr 7 MM law-M,

Patented Aug. l2, 1924.

UNITED STATES 1,504,769 PATENT OFFICE.

HENRY LEJ ITNER, OF LONDON, ENGLAND.

MECHANISM FOR VABYING THEPITGH 01? SCREW PROPELLERS.

Application filed April 21, 1924. Serial No. 708,095.

on each blade stem in the form of a worm-- wheel concentric with thestem and engaging a worm, which is geared by means, such asspur-gearing, to a common wheel which I term a master-wheel. Every bladeis thus geared to this master-wheel so that if this wheel be rotated ineither direction, each blade will rotated on its axis through a certainangle, thereby varying the pitch of the whole propeller. Means are alsodescribed in the said specification whereby the master-wheel can berotated at will.

Now, the object of this invention is to provide improved means forrotating the master-wheel either at the will of the operator, orautomaticall or both, and to this end I proceed as fol ows, that is tosay, con centric with the master-wheel I provide a spur-wheel which maybe locked to, or geared to, or otherwise suitably held to the saidmaster-wheel and meshin with the teeth of this spur-wheel I provi e atoothed quadrant fulcrumed to the hub of the prowheel engaging with it,which in turn will rotate the master-wheel and thereby the propellerbladesthrough the worm-gearing.

Suitable mechanism for swinging the quadrant comprises a rail or rollerfixed to some stationary. art of the engine or machine carrying tiplatter, but movable so that as the prope ler revolves, the rail orroller contacts with some portion of the quadrant and rocks it on. itsfulcrum to alter the pitch of the propeller blades. 'Anto be rotated bother rail or roller applied in the op ositc direction will turn thepropeller bla es in the reverse direction. These rails or rollers may bemoved by suitable means by hand.

To enable the invention to be fully understood I will describe it byreference to the accompanying drawing, in which:

Figure 1 is an elevation of a portion of the hub of a two-bladedscrew-propeller, the blades of which are variable for pitch, havmg myimprovements applied thereto.

Figure 2 is a sectional View at right angles to Figure 1 and Figure 3 isa plan with certain parts removed.

a is'the hub of the propeller and b, b are the cylindrical stems of theblades which are located and turn in the bearings c, c. d, at are theworm-wheels on the said stems and e, a, are the worms gearing therewithand rotatable by spur-wheelsor pinions f, f engaging the common ormaster spur-wheel g.

h is the spur-wheel concentric with the master-wheel g and i isthequadrant the teeth of which mesh with those of the wheel it, so thatwhen the said quadrant is rocked on its fulcrum it will effect therotation of the said wheel h and consequently rotate the master-wheel gto efi'ect the equal rotation of both propeller blades to adjust thepitch angle.

j is one of the rollers whereby the quadrant i is rocked on its fulcrum,the said roller being moved or interposed in the path of another rolleris carried on the said quadrant so as to contact therewith and effectthe required movement. This roller.

1 is shown as being carried by a screwed bolt Z which can be movedlongitudinally by a nut m engaging therewith and adapted a rope or chainm controlled or move in any suitable manner by hand. For moving theuadrant in the opposite direction to that dii'ected by the roller is,another roller, not shown, similar to the roller 7' is employed whichacts upon a second roller n on the quadrant, these two last mentionedrollers being in a different plane from that of the rollers y", 70.

Although I- have described the wheel h as being concentric with themaster-wheel 9 it may be geared thereto and, instead of the quadrant, Imay employ a complete toothed wheel or a toothed rack of a shape in thenature of a cam.

the engine increases its speed the quadrant in engagement with thespur-wheel causes the latter to rotate by virtue of the increase ofcentrifugal force set up in the parts. The blades consequently beingmade to increase their pitch so as to offer more resist ance torotation, and vice versa, thus governing the engine or propeller speed.-Such means may comprise a weight attached to one side of the quadrantand exerting a pull thereon by centrifugal action, a compression or likespring being arranged on the opposite side of the quadrant to return itto its normal position.

Although the invention has been described inconnection with two-bladedpropellers it is to be understood that it may be 'appliedto propellershaving three'or four blades.

Claims:

1. Mechanism for Varying the pitch of screw propellers including apropeller hub, a master wheel, a spur-wheel connected to said masterwheel, a toothed member in gear with said spur-wheel and pivoted to saidpropeller hub, and means interposed in the path of said toothed memberas it is rotated by the propeller hub to cause said toothed member torock on its pivot in either direction whereby the propeller blades arerotated around their axes. 2. Mechanism as claimed in claim 1, whereinsaid spur-wheel is mounted concentrically with said master wheel, andthe toothed member is in theform of a quadrant.

3. Mechanism as claimed in claim 1 wherein said means for causing thetoothed member to rock on its pivot, includes a stationary member androllers on said toothed member adapted to contact with said stationarymember.

HENRY LEITNER.

